Re: [Xen-devel] [RFC v4 2/8] xen/bitops: Rename LOG_2 to ilog2

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Roger,

On 23/01/18 12:10, Roger Pau Monné wrote:
> On Tue, Jan 23, 2018 at 11:44:30AM +0000, Julien Grall wrote:
> > Hi Roger,
> >
> > On 23/01/18 11:39, Roger Pau Monné wrote:
> > > On Mon, Dec 18, 2017 at 08:16:57PM -0700, Sameer Goel wrote:
> > > > diff --git a/xen/include/xen/bitops.h b/xen/include/xen/bitops.h
> > > > index e2019b02a3..a103e49089 100644
> > > > --- a/xen/include/xen/bitops.h
> > > > +++ b/xen/include/xen/bitops.h
> > > > @@ -223,7 +223,7 @@ static inline __u32 ror32(__u32 word, unsigned int shift)
> > > >    #define __L4(_x)  (((_x) & 0x0000000c) ? ( 2 + __L2( (_x)>> 2)) : __L2( _x))
> > > >    #define __L8(_x)  (((_x) & 0x000000f0) ? ( 4 + __L4( (_x)>> 4)) : __L4( _x))
> > > >    #define __L16(_x) (((_x) & 0x0000ff00) ? ( 8 + __L8( (_x)>> 8)) : __L8( _x))
> > > > -#define LOG_2(_x) (((_x) & 0xffff0000) ? (16 + __L16((_x)>>16)) : __L16(_x))
> > > > +#define ilog2(_x) (((_x) & 0xffff0000) ? (16 + __L16((_x)>>16)) : __L16(_x))
> > > Er, why not add a:
> > >
> > > #define ilog2 LOG_2
> > >
> > > On the code that you have to import?
> > There is exactly on caller of LOG_2. So what is the benefits to provide 2
> > names? More that I would expect ilog2 to be used in any code coming from
> > Linux.
> I don't think we should be renaming macros just because we want to
> import verbatim code from Linux or anywhere else, I would rather add a
> linuxkpi.h or similar in order to do the translation, but that's just
> my opinion.
I would have agreed if there was 10-30 callsite in Xen code. For 1 
callsite it sounds like a bit overkill to request to have 2 different 
name. You can see this as renaming very similar to series that rename field.
Cheers,

--
Julien Grall

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